I'm using 3.4.6 in the hexacopter variety. I have tried everything. Also using a m8n gps/compass combo and the gps works great however the compass is never detected? Tried switching out sd cards as another poster stated helped his problem with a similar issue. I've tried different firmware,px4 fw,tried swapping sda/scl around. I have tried loading fw and calibrating thru apm planner,mp,and qgc. I am currently on mission planner with arducopter 3.4.6. Also tried a different gps. None of this has worked? Listed below are the only two device ids that show up? Aren't these both internal? Compass one gives offsets consistently in the 700-800 range on the z axis only so it is unusable. Compass 2 gives offsets in the 200-300 range on all 3 axis and when I try to use it as the primary compass it will fly in loiter but after moving around a bit I start getting compass variance errors and toilet bowling? Any help would be much appreciated,Tks.